arXiv subjects

P. C. Malta

Publications and source records attributed to P. C. Malta.

17 recordsLinked to original sources

arXiv2026

Limits on the Carroll-Field-Jackiw electrodynamics from geomagnetic data

Lorentz-symmetry violation may be described via the CPT-odd, dimension-3, Carroll-Field-Jackiw term, which couples the electromagnetic fields to a constant 4-vector $k_{\rm AF}$ selecting a preferred direction in spacetime. We solve the field equations using the Green's method for a static point-like magnetic dipole and find the $k_{\rm AF}$-dependent corrections to the standard dipolar magnetic field that strongly dominates the near-Earth magnetic field. Given the very good agreement between current models and ground- and satellite-based geomagnetic data, our strongest constraints on the components of $k_{\rm AF}$ in the Sun-centered frame read $|(k_{\rm AF})_Z| \lesssim 4 \times 10^{-25} \, {\rm GeV}$ for $|(k_{\rm AF})_X|, |(k_{\rm AF})_Y| \lesssim 10^{-24} \, {\rm GeV}$ at the two-sigma level. This represents an improvement of about four orders of magnitude over earlier bounds based on other geophysical phenomena.

hep-ph↗

arXiv2025

Experimental signatures of Kalb-Ramond-like particles

We analyse phenomenological signatures of Kalb-Ramond-like particles, described by an antisymmetric rank-2 tensor, when coupled to fermionic matter. The latter is modelled by a tensor current coupled directly to the Kalb-Ramond field or by a pseudovector current coupled to the rank-1 dual of the field-strength tensor. We obtain limits on the coupling constants to fermions and mass of the Kalb-Ramond-like particles by investigating their impact on the hyperfine splittings of hydrogen, the tree-level unitarity of the $S$ matrix for $e^- + e^+ \rightarrow \ell^- + \ell^+$ scattering with $\ell \neq e$ and the differential cross section for Bhabha scattering. Assuming that the couplings to fermions are independent of the fermion species, the strongest 95\%-CL bounds we find are from LEP data at $\sqrt{s} = 136.23$~GeV, namely $g_{\rm PV}/\Lambda \lesssim 6.3 \times 10^{-13} \, {\rm eV}^{-1}$ and $g_{\rm T} \lesssim 1.3 \times 10^{-12} \left( m/{\rm eV} \right)$, both for $m \ll \sqrt{s}$ (here $\Lambda$ is a characteristic energy scale). These limits can be improved in upcoming lepton colliders due to enhanced precision, as well as higher energies.

hep-ph↗

arXiv2024

Bounds on the photon mass via the Shapiro effect in the solar system

We study the effects of a finite mass for the photon on its propagation in a weak gravitational field. In particular, we analyse the gravitational time delay, also known as the Shapiro effect. We work in isotropic coordinates in the weak-field limit and find that the mass-dependent corrections enhance the gravitational time delay. Doppler-tracking data from the Cassini mission allow us to set an upper bound on the photon mass, namely $m_\gamma < 4.9 \times 10^{-7} \, {\rm eV/c^2}$ at $95\%$ CL. We also discuss next-generation solar-system tests of general relativity that could improve this upper limit, potentially by a factor of ten. Though not competitive with the currently best limits, our bound is at the ballpark of earlier ones based on the gravitational bending of light by the Sun.

gr-qc↗

arXiv2023

Shining massive light through a wall

A massive photon possesses a longitudinal polarization mode absent in its massless counterpart. Transverse and longitudinal modes follow different dispersion relations, the latter being much less attenuated than the former when passing through a conductor, suggesting the possibility of isolating longitudinal modes by shining intense light on a conducting wall. We calculate the transmission rates for normal incidence upon a semi-infinite medium and passage through a slab. For the second case we compare the expected photon fluxes with those measurable in current and future light-shining-through-a-wall experiments. Using a 1-MW microwave source as envisaged by the STAX project, a sensitivity at the level of $m_γ< 9.6 \times 10^{-11} \, {\rm eV/c^2}$ could be reached after a run time of an year, with a potential improvement by a factor of $\sim 10^4$ if radio waves of similar power are used.

hep-ph↗

arXiv2022

Constraining the photon mass via Schumann resonances

The photon is the paradigm for a massless particle and current experimental tests set severe upper bounds on its mass. Probing such a small mass, or equivalently large Compton wavelength, is challenging at laboratory scales, but planetary or astrophysical phenomena may potentially reach much better sensitivities. In this work we consider the effect of a finite photon mass on Schumann resonances in the Earth-ionosphere cavity, since the TM modes circulating Earth have eigen-frequencies of order $\mathcal{O} (10 \, {\rm Hz})$ that could be sensitive to $m_γ\approx 10^{-14} \, {\rm eV/c}^2$. In particular, we update the limit from Kroll [Phys. Rev. Lett. 27, 340 (1971)], $m_γ\leq 2.4 \times 10^{-13} \, {\rm eV/c}^2$, by considering realistic conductivity profiles for the atmosphere. We find the conservative upper bound $m_γ\leq 2.5 \times 10^{-14} \, {\rm eV/c}^2$, a factor 9.6 more strict than Kroll's earlier projection.

hep-ph↗

arXiv2022

Phenomenology of a Born-Infeld extension of the $U(1)_{\rm Y}$ sector at lepton colliders

In this work we perform a non-linear extension of the $U(1)_{\rm Y}$ sector of the Standard Model leading to novel quartic effective interactions between the neutral gauge bosons. We study the induced effects through high-energy processes resulting in three photons, namely, Z-boson decay and electron-positron annihilation. Available experimental data on these processes do not yield viable lower bounds on the mass parameter $\sqrtβ$, but we estimate that the range $\sqrtβ \lesssim m_Z$ could be reliably excluded with better statistics in future $e^- e^+$ colliders. We also discuss neutral gauge-boson scatterings, contextualizing our findings with recent results on anomalous quartic gauge couplings.

hep-ph↗

arXiv2021

Lorentz-symmetry violation in the electroweak sector: scattering processes in future $e^+ \, e^-$ colliders

We study CPT-odd non-minimal Lorentz-symmetry violating couplings in the electroweak sector modifying the interactions between leptons, gauge mediators and the Higgs boson. The tree-level (differential) cross sections for three important electroweak processes are discussed: $e^+ \, e^- \rightarrow Z \, H$, $e^+ \, e^- \rightarrow Z \, Z$ and $γ\, γ\rightarrow W^+ \, W^-$. By considering next-generation $e^+ \, e^-$ colliders reaching center-of-mass energies at the TeV scale and the estimated improved precision for the measurements of the respective cross sections, we are able to project upper bounds on the purely time-like background 4-vector as strict as $\lesssim 10^{-5} \, \mbox{GeV}^{-1}$, in agreement with previous work on similar Lorentz-violating couplings.

hep-ph↗

arXiv2020

Constraining hidden photons via atomic force microscope measurements and the Plimpton-Lawton experiment

Modifications to electrodynamics from physics beyond the Standard Model can be tested to a high accuracy. Here we use two setups to place bounds on hidden photons, an Abelian boson kinetically mixed with the photon. The first setup involves atomic force microscope measurements, originally designed to study the Casimir effect at sub-$μ$m distances. The second setup consists of two concentric metal shells with the outer one exposed to a high voltage. By measuring the potential difference between the shells it is possible to test Coulomb's law. The limits obtained here cover regions already excluded, in particular by astrophysical observations, but provide a more direct, laboratory-based confirmation of these bounds.

hep-ph↗

arXiv2020

Testing Lorentz-symmetry violation via electroweak decays

In this work we introduce CPT-odd non-minimal Lorentz-symmetry violating couplings to the electroweak sector modifying the interaction between leptons and gauge bosons. The vertex rules allow us to calculate tree-level processes modified by the presence of the novel dimension-five operators. For definitiveness, we investigate the $W$ decay into a lepton-neutrino pair, the $Z$ decay into pairs of charged and neutral leptons, as well as the decay of the muon. By comparing the experimental measurements on these processes to our results we are able to bound several combinations of the background 4-vectors to be $\lesssim 10^{-4} \, \mbox{GeV}^{-1}$.

hep-ph↗

arXiv2020

A novel test of Lorentz violation in the photon sector with an LC circuit

In the presence of an external magnetic field, the Carroll-Field-Jackiw term introduces a displacement current proportional to the Lorentz-violating background that induces a time-dependent magnetic field. Axion-like particles or hidden photons could generate an analogous signal, potentially detectable with the set-up suggested by Sikivie, Tanner and Sullivan - a sensitive magnetometer coupled to a superconducting LC circuit. We show that a similar set-up, but with an externally driven pick-up loop whose area varies harmonically at $\sim$ Hz, can be used to probe the spatial components of the Lorentz-violating background to the level of $\lesssim 10^{-31}$ GeV. This is eight orders of magnitude more sensitive than previous laboratory-based limits.

hep-ph↗

arXiv2018

Decay photons from the ALP burst of type-II supernovae

We determine limits from SN 1987A on massive axion-like particles (ALPs) with masses in the 10 keV - 100 MeV range and purely coupled to two photons. ALPs produced in the core collapse escape from the star and decay into photons that can be observed as a delayed and diffuse burst. We discuss the time and angular distribution of such a signal. Looking into the future we also estimate the possible improvements if the red supergiant Betelgeuse explodes in a supernova event.

hep-ph↗

arXiv2016

Comparative aspects of spin-dependent interaction potentials for spin-1/2 and spin-1 matter fields

This paper sets out to establish a comparative study between classes of spin- and velocity-dependent potentials for spin-1/2 and spin-1 matter currents/sources in the non-relativistic regime. Both (neutral massive) scalar and vector particles are considered to mediate the interactions between (pseudo-)scalar sources or (pseudo-)vector currents. Though our discussion is more general, we contemplate specific cases in which our results may describe the electromagnetic interaction with a massive (Proca-type) photon exchanged between two spin-1/2 or two spin-1 carriers. We highlight the similarities and peculiarities of the potentials for the two different types of charged matter and also focus our attention on the comparison between the particular aspects of two different field representations for spin-1 matter particles. We believe that our results may contribute to a further discussion of the relation between charge, spin and extensibility of elementary particles.

hep-th↗

arXiv2016

Spin- and velocity-dependent non-relativistic potentials in modified electrodynamics

We investigate the interparticle potential between spin-0, -1/2 and -1 sources interacting in modified electrodynamics in the non-relativistic regime. By keeping terms of $\mathcal{O}( |{\bf p}|^2/m^2 )$ in the amplitudes, we obtain spin- and velocity-dependent interaction energies. We find well-known effects such as spin-orbit couplings, as well as spin-spin (dipole-dipole) interactions. For concreteness, we consider the cases of electrodynamics with higher derivatives (Podolsky-Lee-Wick) and hidden photons.

hep-th↗

arXiv2016

Lorentz violation in simple QED processes

We determine the effect of a CPT-even and Lorentz violating non-minimal coupling on the differential cross sections for some of the most important tree-level processes in QED, namely, Compton and Bhabha scatterings, as well as electron-positron annihilation. Experimental limits constraining the allowed deviation of the differential cross sections relative to pure QED allow us to place upper bounds on the Lorentz violating parameters. A constraint based on the decay rate of para-positronium is also obtained.

hep-ph↗

arXiv2016

Lab-based limits on the Carroll-Field-Jackiw Lorentz-violating electrodynamics

The CPT-odd and Lorentz-violating Carroll-Field-Jackiw modification of electrodynamics is discussed and we study its effects on the energy spectrum of hydrogen, as well as in the generation of a momentum-dependent electric dipole moment for charged leptons. We also briefly comment on the possibility of the detection of Lorentz violation in measurements of vacuum birefringence in resonant cavities. The bounds found are based on local laboratory experimental limits and are not competitive with the ones coming from astrophysical considerations.

hep-ph↗

arXiv2015

Topologically Massive Spin-1 Particles and Spin-Dependent Potentials

We investigate the role played by particular field representations of an intermediate massive spin-1 boson in the context of spin-dependent interparticle potentials between fermionic sources in the limit of low momentum transfer. The comparison between the well-known case of the Proca field and that of an exchanged spin-1 boson (with gauge-invariant mass) described by a 2-form potential mixed with a 4-vector gauge field is established in order to pursue an analysis of spin- as well as velocity-dependent profiles of the interparticle potentials. We discuss possible applications and derive an upper bound on the product of vector and pseudo-tensor coupling constants.

hep-th↗

arXiv2011

Mirror matter, inverse seesaw neutrino masses and the Higgs mass spectrum

In this work we study a mirror model with inverse seesaw neutrino masses in which symmetry breaking scales are fixed from bounds in the neutrino sector. The Higgs sector of the model has two doublets and neutral singlets. The mirror model can be tested at the LHC energies in several aspects. Two very distinctive signatures of the mirror model are a new neutral gauge boson $Z^{\prime}$, with a high invisible branching ratio, and a heavy Majorana neutrino production through the decay $Z^{\prime} \rightarrow N +\bar ν$. This result is compared with heavy Majorana production through heavy pair production and the consequent same-sign dilepton production. The other important consequence of the mirror model is the prediction of the Higgs mass. A particular solution leads to a Higgs in the same region as in the standard model. There is, however, another natural solution where the Higgs mass is above 400 GeV.

hep-ph↗